Exams › JEE Main › Physics

According to the electromagnetic theory of light, the state of polarisation of an electromagnetic wave is defined by

1. the electric field only
2. the magnetic field only
3. both the electric and magnetic fields
4. the direction of propagation

Correct answer: the electric field only

Solution

By convention, the direction of polarisation of an electromagnetic wave is taken as the direction of its electric field vector, because the electric field governs most light-matter interactions (e.g. with charges in detectors).

Related JEE Main Physics questions

• A plane electromagnetic wave falls on a material surface. If it transfers momentum p and energy E, which statement is true?
• For an electromagnetic wave moving in vacuum, the electric field is expressed as E = E₀ sin(kx − ωt). Which of the following quantities does not depend on the wavelength?
• When an electromagnetic wave enters the ionised region of the ionosphere, the moving electron cloud gives rise to a space current, while the electric field also produces a capacitive displacement current. In this situation, what is the phase relation between the space current and the displacement current?
• The rms electric field associated with sunlight is 720 N/C. What is the mean total energy density of this electromagnetic wave?
• The electric field component of an electromagnetic wave in a medium is given by Eₓ = 0, E_y = 2.5 N/C cos[(2π × 10⁶ rad/m)x - (π × 10⁻² rad/s)t] ŷ, and E_z = 0. The wave is:
• A source of monochromatic green light radiates equally in every direction. If it converts only 3% of the 100 W electrical power it uses into electromagnetic radiation, then the electric-field amplitude of the emitted wave at a point 5 m away from the source is closest to:

⚔️ Practice JEE Main Physics free + battle 1v1 →